defrise¶

odl.phantom.geometric.defrise(space, nellipses=8, alternating=False, min_pt=None, max_pt=None)[source]¶

Phantom with regularily spaced ellipses.

This phantom is often used to verify cone-beam algorithms.

Parameters

spaceDiscretizedSpace

Space in which the phantom should be created, must be 2- or 3-dimensional.

nellipsesint, optional

Number of ellipses. If more ellipses are used, each ellipse becomes thinner.

alternatingbool, optional

True if the ellipses should have alternating densities (+1, -1), otherwise all ellipses have value +1.

min_pt, max_ptarray-like, optional

If provided, use these vectors to determine the bounding box of the phantom instead of space.min_pt and space.max_pt. It is currently required that min_pt >= space.min_pt and max_pt <= space.max_pt, i.e., shifting or scaling outside the original space is not allowed.

Providing one of them results in a shift, e.g., for min_pt:

new_min_pt = min_pt
new_max_pt = space.max_pt + (min_pt - space.min_pt)

Providing both results in a scaled version of the phantom.

Returns

phantomspace element: The generated phantom in space.